I have a persistent problem with my Auber temperature gauge giving incorrect temperature readings. I have three Auber SLY 1813 gauges, one for EGT, one for engine water temp and one for the radiator temp. The EGT probe is a TC-KEGT, the engine water temp probe is a PT100A-NPT and the radiator temp sensor is a RTD-Auto.
The gauges are fitted in my Unimog expedition truck. When I switch on the truck in the morning when it is cold (without starting) all three gauges should read the same temperature within a degree or two. The EGT and Radiator temp sensor always read the same, the engine water sensor however sometimes reads the same, sometimes 10-15 Deg C lower. Using a laser temp sensor, I have confirmed that the engine temperature as read by the EGT and radiator temp is correct, and that the PT100A sensor is giving a varying reading. I know I can offset this error, but I should not have to, given the sensor is supposed to be very accurate. I use this sensor to control the electric fans on the radiator, so it is very important to have this working properly. I can't tell whether the offset goes away at higher temperatures or not, and if I put an offset in to correct it when cold, I don't know if the error offset changes if I switch the truck off when hot, and I could be under-reading the engine temperature which will be very bad. Recently I fitted a mechanical thermoswitch for the fans to ensure I don't overheat the engine, but would prefer the Auber gauge to be accurate. I have checked the wiring, and it all seems OK,
I have swapped out the SLY 1813 gauge with some spare ones, and there is no difference, the offset is sometimes there, sometimes not.
This is the second PT100A sensor I have bought, the first would work for a while, then come up with an EEEE error occasionally so I bought a new sensor. Should I try a third PT100A sensor, or is there a more reliable sensor I can buy?